The present invention generally relates to methods and devices for testing electronics, and more particularly to methods and devices for determining the capacitance of a component.
Capacitance is a fundamental parameter of electronic components. It is important for a circuit designer to know a component's capacitance in order to be able to design circuits that will perform as expected. Accurate knowledge of the capacitance of a component allows the circuit designer to select the appropriate component for the circuit. For example, low capacitance components may be desirable for achieving low insertion losses. Also, components having a low capacitance as a function of voltage are desirable for low harmonics. Accordingly, accurate and relevant values of capacitance of components are needed by system designers.
Capacitance measurement of components having a capacitance that is not simply a function of voltage, such as for thyristors, surge protection devices, and bidirectional transient voltage suppressors, can be especially challenging. Such devices typically have diode isolated internal nodes that charge when the diodes are forward biased and remain charged when the voltage is removed. These internal nodes discharge with leakage current over time. During use the nodes are recharged at the signal frequency and therefore often do not have time to discharge. Thus, accurate measurement of the capacitance of such devices is challenging because such measurement is both voltage and time dependent.